refactored cache method to work better with containers and also fast layers

test/unit/Group-test.js

@@ -0,0 +1,50 @@
+suite('Group', function() {
+
+  // ======================================================
+  test('cache group with text', function() {
+    var stage = addStage();
+
+    var layer = new Kinetic.Layer();
+    var group = new Kinetic.Group({
+        draggable : true,
+        x: 100,
+        y: 40
+    });
+    var text = new Kinetic.Text({
+        text : "some text",
+        fontSize: 20,
+        fill: "black",
+        y : 50
+    });
+
+    var rect = new Kinetic.Rect({
+        height : 100,
+        width : 100,
+        stroke : "#00B80C",
+        strokeWidth: 10,
+        cornerRadius: 1
+    });
+    group.add(text);
+    group.add(rect);
+    layer.add(group);
+
+    stage.add(layer);
+
+    group.cache({
+      x: -5,
+      y: -5,
+      width : 110,
+      height : 110,
+      drawBorder: true
+    }).offsetX(5).offsetY(5);
+
+    stage.draw();
+  });
+});
+
+
+
+
+
+
+